Conventional portable wireless communication terminals include a communications transceiver such as a radio frequency transceiver which is responsible for transmitting and receiving wireless communications. The transceiver is typically coupled to a baseband processor, for example a digital signal processor (DSP).
Power consumption in portable wireless communication terminals is of course a critical issue. It is important to enable and disable the various power-intensive transceiver functions in a very precise manner so that a given function is enabled only when (and for as long as) needed, and is otherwise maintained in a sleep (powered-down) state. This precise enabling and disabling of the various transceiver functions is conventionally controlled by the baseband processor, for example, by invoking software interrupts within the baseband processor that are necessary to initiate messaging by way of SPI (Serial Programming Interface), GPIO (General Purpose Input Output), State Machine, etc. to change the power state of various transceiver functions. For example, as shown in FIG. 2, a given transceiver function is conventionally initiated and executed in response to a sequence of 3 interrupt signals received from the baseband processor (DSP in this example). The first interrupt signal 21 causes the associated phase locked loop (PLL), or other frequency generator, to awake from its sleep state at 22. Thereafter, a second interrupt signal 23 causes the remainder of the function (e.g. a receiver function) to power up from its sleep state at 24, and a third interrupt signal 25 causes the function to power down (and thereby return to its sleep state) at 26 after the function has completed its operation.
The number of interrupt signals required to precisely control the power-up and power-down operations of the various transceiver functions has been found in practice disadvantageously to overload the precision timing control capabilities of the baseband processor and degrade overall system power consumption.
Another conventional situation which tends to disadvantageously burden the processing capabilities of the baseband processor is that many emerging wireless data applications often require a transceiver's frequency generator to shift between a small group of frequencies relatively rapidly at predetermined intervals. In conventional wireless communication terminals, the baseband processor must generate and communicate to the transceiver information indicative of the desired group of frequencies and further information indicative of the predetermined time intervals. For example, for each shift from one frequency to another, the baseband processor must communicate to the transceiver (1) that the time for the next frequency shift has arrived, and (2) the frequency to which the frequency generator must shift. This information is communicated from the baseband processor to the transceiver for each frequency shift in a relatively rapid sequence of frequency shifts. Such operation has been found in practice disadvantageously to overload the baseband processor's timing control facilities, and has also been found to consume a disadvantageously large portion of the communication bus between the baseband processor and the transceiver.
It is desirable in view of the foregoing discussion to provide a way of relieving the aforementioned baseband processor and communication bus overloading that can occur in conventional transceiver power control and frequency shift control operations.
According to the invention, baseband processor and communication overloading can be relieved by decentralizing power control and frequency shift control functions that are conventionally concentrated in the baseband processor. A timing sequencer for power control can be integrated into a transceiver of a portable wireless communications terminal, thereby advantageously permitting suitable power control signals to be generated on the transceiver side rather than the baseband processor side. Also, shadow registers containing information indicative of commonly used or repeated frequencies can be integrated into the transceiver side, thereby advantageously relieving the baseband processor and the communication bus of corresponding frequency shift control responsibilities. These frequency shift control responsibilities can be further relieved according to the invention by integrating into the transceiver side a sequencer cooperable with the shadow registers for controlling the frequency shifting of the frequency generator, and by integrating into the transceiver side further shadow registers for programming the sequencer with desired frequency shift sequences.